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Ann Thorac Surg 1995;59:178-182
© 1995 The Society of Thoracic Surgeons
National Naval Medical Center and the Uniformed Services University of the Health Sciences, Bethesda, Maryland
Accepted for publication July 26, 1994.
| Abstract |
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| Introduction |
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A second primary lung cancer may develop in patients who have undergone successful resection of a bronchogenic carcinoma. In up to 10% of patients with surgical stage I bronchogenic carcinoma, a second primary lung cancer will develop, with an average incidence of 2.2% per year [1]. Early detection of a second or third primary lung cancer followed by surgical resection is associated with a 33% 5-year survival rate and offers the best chance for cure [2, 3]. Most such patients have limited pulmonary function due to the effects of smoking and previous lung resection. Therefore, lung-sparing procedures are generally recommended for resection of the new tumor [24].
Although conservative resection is desirable, it is not always feasible. The location or size of the new tumor may necessitate an extensive resection, even pneumonectomy, if the patient is to have a chance for cure. When the new primary lung cancer forms in the lung contralateral to the first tumor, it has been recommended that ``a lobectomy or lesser procedure may be considered'' [4]. This implies that a pneumonectomy is contraindicated once a patient has undergone a contralateral lung resection. In fact, only two cases in which a pneumonectomy was performed after contralateral lobectomy have been reported in the literature [5]. There may be two explanations for this: suitable candidates for the procedure are exceedingly rare, or the procedure is generally regarded as too radical.
We have recently successfully carried out three left pneumonectomies in patients who had undergone right upper lobectomies for carcinoma, all within a span of 6 months. Preoperative evaluation to determine the patient's operability, including pulmonary function tests coupled with quantitative perfusion lung scans, predicted that all 3 patients could tolerate pneumonectomy.
| Material and Methods |
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Patient 3
A 58-year-old man who had undergone a right upper lobectomy in 1986 for a T2 N0 M0 adenocarcinoma was found to have a second lung cancer in 1993. At bronchoscopy, the tumor was found to involve both the left upper and lower lobe bronchi. He was working daily as a machine parts clerk. He had a history of hypertension and alcoholism, but these were both controlled; he had also undergone abdominal aneurysmectomy and suffered a myocardial infarction. He was judged to be in fair physical condition. The findings from preoperative bronchospirometry plus quantitative perfusion lung scanning predicted an FEV1 of 1.03 L after left pneumonectomy. At thoracotomy, a lesser resection was deemed impossible. Intraoperative measurement of the central pulmonary artery pressure before and after cross-clamping of the left pulmonary artery revealed a mean pulmonary artery pressure of 30 mm Hg, which was considered acceptable. The left pneumonectomy was completed and the patient's postoperative course was uneventful. He was discharged on the thirteenth hospital day and provided with supplemental oxygen. At follow-up 2 months after operation, he was relatively well and was able climb 54 steps with supplemental oxygen. The results of pulmonary function tests at that time are listed in Table 2
. The supplemental oxygen therapy was eventually discontinued. Five months after his operation, he died of complications of acute alcohol intoxication.
| Comment |
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Although conservative resection is the goal, careful preoperative evaluation should always determine whether the patient can tolerate maximum resection, should it prove necessary. In some cases, resections larger than a lobectomy may be required to remove a second malignancy. A prior lobectomy in the contralateral lung should not in itself be a reason for excluding such patients from the chance for cure. Commonly used guidelines for determining operability in other candidates for lung resection should apply to these patients as well [9]. That is, if the patient's physical condition is fair, and pulmonary function after the procedure is predicted to be adequate, then even a pneumonectomy may be attempted after a contralateral lobectomy.
The postpneumonectomy pulmonary function can be reliably predicted preoperatively using bronchospirometry coupled with the quantitative perfusion lung scan [7]. A predicted postoperative FEV1 of at least 800 mL has become a widely used criterion for identifying lung resection candidates [9]. The rationale for this cutoff has its basis in clinical experience: an FEV1 of less than 750 mL is associated with a median survival of only 3 years in patients with chronic obstructive pulmonary disease [10]. Additionally, Boysen and colleagues [11] reported a reasonable perioperative mortality rate and a low rate of respiratory deaths in the first postoperative year for a group of 38 pneumonectomy patients with a preoperative FEV1 of less than 2.00 L but a predicted postpneumonectomy FEV1 of greater than 800 mL.
The same criterion, a predicted postoperative FEV1 of at least 800 mL, was applied in the present series of patients. Actually, the predicted postpneumonectomy FEV1 in each patient was at least 1.00 L, so all 3 qualified for left pneumonectomy preoperatively. The need for a pneumonectomy was known preoperatively only in patient 2, based on bronchoscopic findings. The extent of resection necessary in the other 2 patients became apparent only after surgical exploration. Interestingly, the measured postoperative FEV1 was strikingly higher than that predicted on the basis of the lung scan findings (see Table 2
), a phenomenon previously noted by Williams and associates [12] in more than half of their patients who underwent pneumonectomy. This underestimate allows for a certain safety margin in favor of the patient.
Results from additional tests done in 2 of our patients before resection also suggested that left pneumonectomy would be tolerated. The maximum oxygen consumption during exercise, a global assessment of cardiopulmonary fitness, was measured preoperatively in patient 2 and found to be 15.7 mL kg-1 min-1. Although a preoperative value of less than 10 mL kg-1 min-1 has been associated with increased morbidity and mortality in the setting of pulmonary resection [13], the cutoff value for excluding patients from potentially curative resection remains undetermined [14]. Before resecting the left lung in patient 3, we measured the proximal mean pulmonary artery pressure intraoperatively before and after occlusion of the left pulmonary artery. Experience with this technique in the setting of pneumonectomy has been described, and values greater than 33 mm Hg after ligation of the ipsilateral pulmonary artery were found to be associated with a high rate of mortality [15]. However, 8 of 12 patients in that series with levels exceeding 33 mm Hg survived the potentially curative resection, so the value that contraindicates pneumonectomy is unclear. Nevertheless, when the proximal mean pulmonary artery pressure stays below this level during ligation, as it did in our patient 3, the surgeon may feel more confident about proceeding.
Twelve patients who underwent pneumonectomy followed by lobectomy have been reported on, and, in those 11 whose sides were specified, the combination always involved the left lung and a right lobe or lobes (Table 3
). Four patients in the total series summarized in Table 3
died (23.5%) in the immediate postoperative period. The lung and lobe were not specified in 1 [20]. Two patients [5, 17] underwent left pneumonectomy and right lower lobectomy, and the fourth underwent a left pneumonectomy followed by a right upper lobectomy. Anatomic and functional considerations probably explain this. The contribution each lobe makes to the total lung volume appears to correlate with the number of segments in that lobe [26]. Resection of the right lung and either one of the left lobes (four segments in each) would leave the patient with about 24% of his or her original lung volume [26]. This may be too low for most patients. Conversely, a pneumonectomy and contralateral lobectomy would be best tolerated when it involves the left lung and right middle lobe (two segments). The second-best combination would be the left lung and right upper lobe (three segments). The combination of left pneumonectomy and right lower lobectomy (five segments) has been performed in 2 patients with lung cancer, and both patients died perioperatively due to cardiopulmonary causes [5, 17].
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Although lobectomy has been considered contraindicated after a patient has undergone pneumonectomy on the opposite side [4, 27], we believe the converse, a pneumonectomy after a contralateral lobectomy, is not an equivalent situation, and may even be better tolerated. When a pneumonectomy is done after a contralateral lobectomy, it involves no intraoperative manipulation of the residual lung with resultant tissue edema and atelectasis, as might occur when a lobectomy is performed after pneumonectomy. Additionally, the nonoperated hemithorax will be less painful, so that the patient's ability to cough is better postoperatively.
The potential for cardiopulmonary disability in long-term survivors of pneumonectomy and lobectomy appears to be considerable. Without equivalent data for such patients, however, one can only extrapolate from the results of functional and physiologic studies performed in patients after pneumonectomy only. In postpneumonectomy patients, exercise limitation of varying degrees is universal, and tends to be worse when the person is older, has had a reduced maximum breathing capacity preoperatively [28], or has heart disease [29]. When the remaining lung is abnormal, pulmonary arterial hypertension is common postoperatively, although cor pulmonale is rare [29]. This should certainly apply in our patients, in whom the cumulative effects of smoking and prior lung resection had substantially impaired the function of the remaining lung and diminished the size of the residual pulmonary vascular bed. Those with less pulmonary perfusion before pneumonectomy would likely be at higher risk for suffering pulmonary hypertension and cor pulmonale after resection. However, because the FEV1 correlates well with the degree of pulmonary perfusion impairment found in patients with chronic obstructive lung disease [30], its use as a criterion for determining operability may actually help in the effort to ensure that the pulmonary vascular reserve will be adequate after pneumonectomy.
Conservation of functional lung is a guiding principle in the management of a second carcinoma of the lung, but this effort to conserve must not jeopardize the patient's chance for cure. With the increasing recognition of cases of metachronous lung cancer, other surgeons will be faced with patients similar to ours. Deciding whether a patient will tolerate a pneumonectomy remains a challenging matter in the setting of a previous contralateral lobectomy. It appears that bronchospirometry, coupled with quantitative perfusion lung scanning, remains an excellent tool for predicting postoperative pulmonary function and operability, even in these patients. Our experience suggests that a previous contralateral lobectomy should not be used as a basis for ruling out a potentially curative pneumonectomy when the predicted postpneumonectomy FEV1 is 1.00 L or greater.
| Footnotes |
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| References |
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